DMA based characterization of stiffness reduction in long fiber reinforced polypropylene

Brylka, Bartholomäus; Schemmann, Malte; Wood, Jeffrey; Böhlke, Thomas

doi:10.1016/j.polymertesting.2017.12.025

Cited by 20 publications

(14 citation statements)

References 21 publications

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“…In order to remain below this value, for the statical preload ε stat =0.1 % , and for the amplitude of the harmonic load ε dyn =0.05 % is chosen. Furthermore, loads in this range are commonly used for thermoset and thermoplastic polymers . The fiber‐reinforced specimens are evaluated for 0°, 45° and 90° directions with respect to the direction of injection.…”

Section: Dynamic Mechanical Analysis Of Polymersmentioning

confidence: 99%

“…Furthermore, loads in this range are commonly used for thermoset and thermoplastic polymers. [11,30,31] The fiber-reinforced specimens are evaluated for 0 • , 45 • and 90 • directions with respect to the direction of injection. The storage modulus E ′ and the loss factor tan are depicted over temperature in Figure 3 for three frequency decades.…”

Section: Dma For Tension Mode For Different Temperature and Frequencymentioning

confidence: 99%

“…In the study by Thomason, the thermomechanical and viscoelastic material properties represented by the stiffness and damping properties in case of a glass fiber‐reinforced epoxy composite were discussed. In the context of a long fiber‐reinforced polypropylene (PP), investigations with respect to the nonlinear time‐, temperature‐ and frequency‐dependent material behavior were carried out by Brylka et al. The viscoelastic material behavior can be mathematically described through rheological models, consisting of simple mechanical elements such as springs and dashpots .…”

Section: Introductionmentioning

confidence: 99%

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Dynamic mechanical analysis of pure and fiber‐reinforced thermoset‐ and thermoplastic‐based polymers and free volume‐based viscoelastic modeling

et al. 2018

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Fiber‐reinforced polymer composites have gained significant importance in engineering applications and are widely used as structural components. The optimal choice of combinations of the type of polymer matrix and the fiber content depend on the required applications. In view of this, polypropylene (PP), a thermoplastic, reinforced with 30 wt.% of short glass fibers (PP‐GF30) is considered for this study. Additionally, a rather new composite system based on unsaturated polyester‐polyurethane hybrid resin (UPPH) is introduced. This thermoset‐based material is reinforced with 41 wt.% of long discontinuous glass fibers (UPPH‐GF41). Dynamic mechanical analysis (DMA) is performed on the pure polymer and the composite samples to experimentally characterize the temperature‐ and frequency‐dependent material behavior. It is observed that the stiffness of the materials is highly temperature‐dependent. PP exhibits a nonlinear viscoelastic behavior in the temperature range of possible applications whereas the UPPH material shows a less pronounced behavior. The resulting experimental data not only give general information on the material behavior of the composite subjected to a temperature and frequency load but also provide input as well as validation data for the developed material modeling methods. In an industrial environment, homogenized elastic material properties are desirable for analysis of the structural components at room temperature conditions. A mean field homogenization method is introduced to estimate the effective elastic material properties on a macroscopic scale. This method is formulated explicitly in terms of orientation tensors of second‐ and fourth‐order, describing quantitatively the microstructure of the corresponding composite. Additionally, the thermoviscoelastic material behavior for the considered temperature range is modeled by the free volume concept. In this context, the material parameters for the pure PP and UPPH material are identified. The calculated simulation results are compared with the experimental data entailing good agreements.

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Section: Dynamic Mechanical Analysis Of Polymersmentioning

confidence: 99%

Section: Dma For Tension Mode For Different Temperature and Frequencymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Dynamic mechanical analysis of pure and fiber‐reinforced thermoset‐ and thermoplastic‐based polymers and free volume‐based viscoelastic modeling

et al. 2018

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“…The authors, however, did not aim to characterize the anisotropic damage behavior of SMC, as the number of experiments was significantly too low and the differentiation of damage, viscoelasticity, and plasticity in discontinuous fiber reinforced polymers [30] along with their parameter identification are still not fully understood. One result could be an understanding of the anisotropic stress-strain behavior of SMC.…”

Section: Discussionmentioning

confidence: 99%

Cruciform Specimen Design for Biaxial Tensile Testing of SMC

Schemmann¹,

Lang²,

Helfrich

et al. 2018

J. Compos. Sci.

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This paper presents an investigation of different cruciform specimen designs for the characterization of sheet molding compound (SMC) under biaxial loading. The considered material is a discontinuous glass fiber reinforced thermoset. We define various (material-specific) requirements for an optimal specimen design. One key challenge represents the achievement of a high strain level in the center region of the cruciform specimen in order to observe damage, at the same time prevention of premature failure in the clamped specimen arms. Starting from the ISO norm for sheet metals, we introduce design variations, including two concepts to reinforce the specimens' arms. An experimental evaluation includes two different loading scenarios, uniaxial tension and equi-biaxial tension. The best fit in terms of the defined optimality criteria, is a specimen manufactured in a layup with unidirectional reinforcing outer layers where a gentle milling process exposed the pure SMC in the center region of the specimen. This specimen performed superior for all considered loading conditions, for instance, in the uniaxial loading scenario, the average strain in the center region reached 87% of the failure strain in a uniaxial tensile bone specimen.

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“…Three types of FRPC using long, continuous, and short fibers are typically used for weight reduction as an alternative to metals 5–7 . Long FRPC have been used due to their high mechanical stiffness and productivity, despite a drawback of anisotropic properties in the case of external multi‐axial load 8–10 . Continuous FRCP have been used for parts carrying high load, such as structural frames, despite their low productivity 11–14 .…”

Section: Introductionmentioning

confidence: 99%

Circular braided glass fiber/epoxy composites with helical architecture (coil spring) fabricated by plaster‐sacrificial compression molding for structural automotive applications

Kim

Shin²,

Kim³

et al. 2020

J of Applied Polymer Sci

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Various approaches to reduce the weight of electronics and automobile devices have been explored. For instance, an alternative polymer was utilized to replace metals. In the present study, a new circular braided glass fiber/epoxy composite (braid angle: 45°, fiber: 48 vol%) with a helical structure was fabricated as a model coil spring for weight reduction. A plaster‐sacrificial compression mold was especially designed to fabricate helical composites without voids. The spring design was validated by the experimental results of torsional tests. Plastic deformations of the epoxy resin were measured using creep tests to eliminate high‐temperature plastic deformation (HTPD) of the composites. Pre‐strain applied thermal aging was utilized to remove HTPD. Mechanical properties of the composites were also investigated. The mechanism of mechanical failure was found to be the interfacial failure. For preparation of uncured prepreg, resin permeability was measured to a range of 10−10 m2. Resin transfer in the glass fiber‐braided textiles occurred due to the combination of viscous and diffusional flow mechanisms. Based on the results in this study, the facilely designed coil spring composite can be used for various applications, especially automotive parts.

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DMA based characterization of stiffness reduction in long fiber reinforced polypropylene

Cited by 20 publications

References 21 publications

Dynamic mechanical analysis of pure and fiber‐reinforced thermoset‐ and thermoplastic‐based polymers and free volume‐based viscoelastic modeling

Dynamic mechanical analysis of pure and fiber‐reinforced thermoset‐ and thermoplastic‐based polymers and free volume‐based viscoelastic modeling

Cruciform Specimen Design for Biaxial Tensile Testing of SMC

Circular braided glass fiber/epoxy composites with helical architecture (coil spring) fabricated by plaster‐sacrificial compression molding for structural automotive applications

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